The present invention relates generally to data transport and in particular to a method and apparatus for sending and receiving messages between two nodes in a communications system.
Signaling system number 7 (SS7) is a digital signaling standard developed by the International Telecommunication Union (ITU)xe2x80x94Telecommunications Standard Society (TSS). SS7 is the protocol for data communications in a communications system. In communications systems, a SS7 network is present, which is separate from the voice network. The SS7 network is used solely for the purpose of switching data messages pertaining to the business of connecting telephone calls and maintaining the signaling network. Common Channel Signaling (CCS) is the technology used in SS7 networks. CCS uses a digital facility, but places signaling information in a time slot or channel separate from the voice and data to which it is related. This mechanism allows signaling information to be consolidated and sent through its own network apart from the voice network. A packing switching system is the mechanism used for transferring messages throughout the network.
All nodes in a SS7 network are called xe2x80x9csignaling pointsxe2x80x9d. A signaling point has an ability to perform message discrimination (read the address and determine if the address is for that node), as well as to route the SS7 messages to another signaling point. The main type of signaling points is a service switching point (SSP), which is a local exchange in a telephone network. A SSP may be a combination of a voice switch and a SS7 switch, or an adjunct computer connected to the local exchange""s voice switch. The SSP provides the functionality of communicating with the voice switch via the use of primitives and creating packets, or signal units needed for transmission in a SS7 network. Another signaling point is a signal transfer point (STP), which serves as a router in the SS7 network. All SS7 packets travel from one SSP to another through the services of a STP. Another signaling point is a service control point (SCP), which serves as an interface to telephone company databases.
SS7 is used in cellular networks to provide signaling information required to establish and disconnect circuit connections, as well as share database information from one institute to another. A mobile switching center (MSC) in a communications system connects to the SS7 via a signaling transfer point. The SS7 network is instrumental in collocating all the cellular providers together and allowing their various databases to be shared with each other. For example, the home location register (HLR) is a database used to store information about users of a cellular network. A visitor location register (VLR) is a database used to store temporary subscriber information when that subscriber is visiting the coverage area. This information is retrieved from the subscriber""s HLR. With SS7 signaling through a SS7 network, data stored in a HLR can be stored with other MSCs across the SS7 network.
With the rapid expansion of communication systems, such as cellular networks, the expansion of SS7 networks has been limited and regulated. Concerns about capacity of SS7 links and the cost associated with expanding and creating SS7 networks for communication systems has made the development and expansion of communication systems, such as cellular systems, costly. In addition, with increased traffic on SS7 networks, concerns regarding congestion and flow control are present.
Therefore, it would be advantageous to have an improved method and apparatus for transporting messages in a SS7 network.
The present invention overcomes congestion and flow concerns in signaling networks, such as SS7 networks, by providing a virtual communications link or connection between various nodes in a SS7 network. The virtual link is provided by gateways, which send SS7 messages over a network link, such as an Internet protocol link. The present invention provides a method, apparatus, and instructions for establishing a virtual communication channel between applications on different nodes in which one node may be using a communication protocol stack based on one protocol, such as SS7, and another node may be using a communication protocol stack based on another protocol, such as IP. Alternatively, a virtual communication channel may be provided between applications on different nodes in which both nodes use a communication protocol stack based on IP to communicate with each other, but carry SS7 traffic through the communication channel. A gateway is provided in which both SS7 and IP are supported. The gateway allows for logical transport of signaling messages between peer applications on different nodes. Messages for SS7 are placed in data packets for transport to a destination using an IP connection or link to the destination. Header information also is placed into the data packet to allow for routing of the messages when the packet is received at the destination.
The link or connection may be to another gateway or to a node, which extracts the message and header information from the data packet and sends it on to the appropriate node using the header information.
The mechanism of the present invention provides for internetworking addressing schemes between both SS7 and Transport Control Protocol/Internet Protocol (TCP/IP). In addition, the present invention allows for addition of nodes without requiring expansion of an existing SS7 network.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.